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Measurement and correlation of flow-boiling heat transfer of a R410A/oil mixture inside a 4.18 mm straight smooth tube.

Author(s) : HU H., DING G., HUANG X., et al.

Type of article: Article

Summary

Two-phase flow patterns and heat transfer characteristics of a R410A/oil mixture flow boiling inside a horizontal straight smooth tube with the inside diameter of 4.18 mm were investigated experimentally. The flow pattern observations for a R410A/oil mixture match well with the flow pattern map of Wojtan et al. by using the refrigerant-oil properties instead of pure-refrigerant properties. The test results show that the heat transfer coefficient of a R410A/oil mixture increases with mass flux of a refrigerant-oil mixture; the presence of oil enhances the heat transfer by a maximum of 60% at the range of low and intermediate vapour qualities. There is a peak of local heat transfer coefficient at about 2-5% nominal oil concentration at higher vapour qualities, and the peak shifts to lower nominal oil concentration with the increase of vapour qualities. Higher nominal oil concentration gives a more detrimental effect at high vapour qualities. A new correlation to predict the local heat transfer of a R410A/oil mixture flow boiling inside the horizontal smooth tubes was developed based on flow patterns and local properties of a refrigerant-oil mixture. The new correlation agrees with 92% of the experimental data of R410A/oil in a 4.18 mm horizontal smooth tube within a deviation of plus or minus 30%, and it agrees with 96% of the experimental data of a R410A/oil mixture in a 6.34 mm horizontal smooth tube within a deviation of plus or minus 20%.

Details

  • Original title: Measurement and correlation of flow-boiling heat transfer of a R410A/oil mixture inside a 4.18 mm straight smooth tube.
  • Record ID : 2010-0047
  • Languages: English
  • Source: HVAC&R Research - vol. 15 - n. 2
  • Publication date: 2009/03

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